In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, for future generations of mobile communications systems frequency bands at many different carrier frequencies could be needed. For example, low such frequency bands could be needed to achieve sufficient network coverage for wireless devices and higher frequency bands (e.g. at millimeter wavelengths (mmW), i.e. near and above 30 GHz) could be needed to reach required network capacity. In general terms, at high frequencies the propagation properties of the radio channel are more challenging and beamforming both at the network node at the network side and at the wireless devices at the user side might be required to reach a sufficient link budget.
The wireless devices and/or the transmission and reception point (TRP) of the network node could implement beamforming by means of analog beamforming, digital beamforming, or hybrid beamforming. Each implementation has its advantages and disadvantages. A digital beamforming implementation is the most flexible implementation of the three but also the costliest due to the large number of required radio chains and baseband chains. An analog beamforming implementation is the least flexible but cheaper to manufacture due to a reduced number of radio chains and baseband chains compared to the digital beamforming implementation. A hybrid beamforming implementation is a compromise between the analog and the digital beamforming implementations. As the skilled person understands, depending on cost and performance requirements of different wireless devices, different implementations will be needed.
One purpose of so-called beam management is for the network node to keep track of its served wireless devices with narrow beams (as used at the TRP and/or the wireless devices) in order to increase coverage and throughput. Due to rotation, movement and/or blockage of the served wireless devices the beam (at the TRP and/or wireless devices) needs to be updated dynamically in order to maintain good channel quality between the network node and the served wireless devices. In case an operative connection between a served wireless device and the network node is lost, for example due to blockage, a beam recovery procedure can be initiated to re-establish the beam connection. Such beam recovery procedure could, for example, involve sweeping through all different combinations of beams, both at the TRP and at the wireless device. When there are many candidate beams such beam sweeping procedure could be costly in terms of time consumption and overhead signaling. Beam training might require large overhead signaling and time consumption especially for analog and hybrid antenna array implementations where beams must be swept in a sequential manner. If antenna arrays with analog beamforming are used at both the TRP and the wireless device this becomes even more challenging since, in an exhaustive beam search, for each TRP beam all candidate beams at the wireless device need to be tested.
Hence, there is still a need for improved beam management.